A number that is written as a sum of single-digit multiples of powers of 10 is called its expanded form. In this representation, each digit is expressed as a multiple of a power of ten, reflecting the place value of each digit in the number. For example, the number 345 can be expressed in expanded form as:
3 × 100 + 4 × 10 + 5 × 1
This shows the contribution of each digit based on its position in the number.